Growing md0 by larger disk - which is best method.

["R. Ramesh" <rramesh@verizon.net>]

I have a mdadm implemented raid5 with 3 disks (2x 3TiB and 1x 2TiB). 
Each disk has one partition only for the full size of that disk and the 
partitions are then combined in to md0.

I like to swap out the 2TiB with a new 3TiB. While I do not expect issue 
with this, a lot of reading about unrecoverable errors spooked me a 
little on the rebuild/resync. Further, I think it is silly that we need 
to read all the disks in the original array as part of resync (in a 
fail+remove+add method of changing disks)  Is there a way to avoid 
resync by doing a dd from 2TB on to the *new* 3TB and then reassembling 
the array? I mean this

  1. shutdown
  2. add 3tb to the PC
  3. boot using rescue disk and do not assemble the md0.
  4. Copy partition table from one of  old 3TiB on to the *new* 3TiB
  5. dd 2TiB-part1 to *new* 3TiB-part1
  6. shutdown
  7. disconnect 2TiB disk
  8. restart to original OS on the disk to find the 3TiB as part of the
     reassemble
  9. Grow the array to full size


Since the above is not suggested anywhere I could find, I like to know 
what I am missing as this seems too easy to me.

Ramesh